1. Field of the Invention
The present invention relates to a water jet spray device that is particularly useful in the hydroentanglement of fibres in nonwovens. Hydroentanglement involves sending a curtain of jets of water under pressure onto a web of fibres to entangle them and form them into a coherent web, without requiring the use of binders or resins.
2. Description of the Related Art
EP-0 725 175 discloses a water jet spray device comprising a pressure-resistant body defining an internal chamber. The oblong cylindrical internal chamber has one entrance, and preferably two entrances, one in each end face, and communicates, through an interposed perforated plate, with an outlet leading out of the body. The perforated plate is in contact with a seal. To facilitate replacement of the annular seal applied to the perforated plate, without the chore of removing screws and disassembling it, there is provided, all the way along the length and across the width of a groove containing the seal, a repair groove whose height is approximately the same as the thickness of the seal and a longitudinal metal sheet can be inserted into this repair groove, this longitudinal metal sheet having, on its lower face, a device for gripping the seal. To replace the seal which is removed as best one can, the metal sheet with a new seal is put into the repair groove and, with the aid of a tool, the new seal is rolled down where it must slide into the groove where it is to be housed. DE-A-199 21 694 improves on the device disclosed in EP 0 725 175 in order to simplify the fitting process. For this purpose it uses a seal holder of circular cross section that also carries the perforated plate. In the factory, the seals are placed in the seal holder and the seal holder is put into position in the body once for all, before installing the body. If the seal wears out, though it is emphasized that this rarely happens, it is easily replaced in the manner disclosed in EP-0 725 175. Experience has shown that performing these seal replacing operations is an operation that demands too much skill to be carried out in a short space of time, especially when it comes to very long seals measuring several meters.
U.S. Pat. No. 5,042,722 discloses a water jet spray device having a pull-out cassette in a body and comprising a perforated plate, a seal holder and a spacer. Just as in the previous documents, the cassette is large and therefore requires a large hole to be made in the body. This is undesirable from the point of view of pressure resistance, and replacing the perforated plate and/or the seal holder is a complicated task, since the spacer has to be unscrewed to allow access to the perforated plate.